Marantz 3800 - Section 2 MAINTENANCE; General Maintenance Guidelines; Preamplifier Circuits: Tests and Adjustments

Section
2
MAINTENANCE
1.
GENERAL
Section
2
contains
maintenance
procedures
for
service,
troubleshooting,
removal/installation,
and
repair
of
the
Model
3800.
Service
procedures
include
required
alignments,
tests,
and
adjustments
described
for
failures
or
malfunctions.
Trouble-
shooting
procedures
include
isolating
and
identify-
ing
both
mechanical
and
electrical
malfunctions.
Removal/installation
procedures
include
unit
dis-
assembly
and
reassembly
for
component
repair
or
replacement.
Performance
evaluation
tests
and
service
of
the
Model
3800
should
be
undertaken
only
by
an
experienced
technician,
one
knowledgeable
in
solid
state
preamplifiers
and
the
use
of
sensitive
test
equipment.
All
instructions
should
be
read
carefully
and
understood
fully
before
proceeding
with
any
service.
To
better
understand
the
functions
of
the
Stereo
Control
Console,
consult
the
Schematic,
Wiring,
and
Dolby
Processing
Diagrams.
Marantz
will
issue
supplementary
Technical
Service
Data
to
all
authorized
facilities
for
upgraded
service
and
product
support.
Marantz
requests
field
service
problems
and
suggestions
for
im-
provement
be
sent
to
the
Technical
Services
Manager
at
our
corporate
location.
CAUTION:
WHEN
ADJUSTING
OR
_IN-
STALLING
PARTS,
DO
NOT
OVER
TIGHTEN
MACHINE
SCREWS
OR
ADJUST
NUTS.
EX-
CESSIVE
FORCE
CAN
EASILY
DAMAGE
THE
ALUMINUM
ALLOY
PARTS.
NOTE:
Isolate
troubles
with
an
oscilloscope
commonly
used
with
standard
audio
frequen-
cies.
Measure
voltage
and
resistance
with
a
volt-ohmmeter
with
sensitivity
of
20
K
ohms-
per-volt
or
greater.
Hand
tools
should
be
small
instrument
type
to
minimize
scratching
the
finish.
2.
PREAMPLIFIER
CIRCUITS
TESTS
AND
ADJUSTMENTS
A. TEST EQUIPMENT
Test
and
adjustments
in
the
following
para-
graphs
are
based
on
the
use
of
the
Recom-
mended
Test
Equipment
listed
in
Table
2-1
or
their
equivalent.
A.C.
Power
Control
Box
and
Test
Equipment
Connection
Diagrams
are
shown
in
Figures
2-1
and
2-2
respectively.
B.
PRELIMINARY
CONDITIONS
(1)
Set
controls
on
A.C.
Power
Control
Box
as follows:
Line
Switch.
........0
eee
reese
Off
Phase
Switch......-.--220ee85
Normal
Wattmeter
Switch.
.....--+-.++ee5:
In
Autotransformer
...
Minimum
(Full
ccv)
(2)
Set
Model
3800
Panel
switches
and
con-
trols
to
their
normal
settings
except
as
noted:
Program
Selector.......----+555
AU
X
TAPE:
COPY
:'i
essoedin
oad
eee
We
des
Out
MODE
.co45
Sewer
ey
STERE
O
TAPE
MONITOR...........
SOURCE
TONE,
BALANCE.........+-5
Center
TURNOVER,FILTERS,
LOUDNESS
.0
ut
DOLBY
fot
One
ss
Shea
ds
OFF
VOLUME........
Minimum
(Full
cow)
TAPE
REC-EQ..........-0
ees
O
ut
TONE
DEFEAT.......----5
20
ees
In
RECORD
LEVEL..........--
Ful
cw
PIEAY.
CAL
teenie
ee
el
eters
ec
Fullccw
LRMETER.........----005
L
(Oust)
400
Hz
TONE.......
2
eee
ees
Out
SPEAKERS
be
oe
ise
diee
ie
eehelei
es
Out
POWER
chs
coh
bade
hess
On(I
n)
(3)
Install
shorting
plugs
in
AUX
INPUT
jc
ks.
2-1